Copper base allots



Patented Sept. 12,1939

fuNiTE-n srAT s PATENT OFFICE COPPER BASE ALLOYS Werner Hessenbruch, Hanau-on-the-Main, Germany, assignor. to Heraeus-Vacunmsehmelze, 'A. G., Hanau-on-the-Main, Germany I No Drawing. Application July 1a, 1938, Serial No. 219,999. In Germany November 1, 1935 '4 Claims.

This invention relates to copper base alloys and the invention is particularly concerned with a copper-beryllium ,alloy containing an addition stance, as nickel, iron and silicon, certain lmprovements were eflected, notably refinement of gra'n structure. Such ternary alloys have been, of advantage for a number or purposes, but have so also had some disadvantages, the nature of which I will appear more fully hereinafter, although it may here be not impaired.

g5. 1 have found that by employing cobalt as an addition element to make a ternary copper ber'yl-q lium alloy, especally where the quantity of cobalt usedlies within the ranges hereinafter specified,

a number of substantial advantages are obtained 30 in comparison with other ternary alloys of this general type.

One of the outstanding improvements of the present invention is maintenance 01' relatively high electrical conductivity, even when the alloy 35 is hardened to a highdegr'ee.

I have further found that ,cobalt not, only makes possible the production oia fine grain structure, but still more important, affords improved 'controiiability as to grain size. These Q characteristics are aflorded, moreover, while,

maintaining a higher degree of electrical conductivity than has been possible heretofore; when I using other addition ingredients.

The alloy of the present invention' -ls seem-- an proved as compared with prior alloys ofthe type under consideration because of increased tensile strength; especially after. substantial cold working, such as drawing or a wire or similar piece. An important consideration' in alloys'of the a general typehere involved is" the employment,

of the lowest possible beryllium content,.pa'rticularly in view of the relatively high price of beryllium. The amount of beryllium required may be reduced in accordance with the present invention by the addition oi the cobalt.

other desirable physiv V that the electrical conductivity of these prior ternary alloys ,wassomewhat As brought out inv my copending application Serial No. 107,948, of which the present application is ln part a division, heat treatment suitable for alloys 01' the type here under consideration may be effected by quenching from temperatures ranging between 500 C. and 800 0., and subsequently tempering at temperatures between 250 C. and 500 C. Between the quenching and the tempering or after the tempering the alloys can also be cold worked if desirable.

By variations in heat treatment some changes in physical properties may be brought about, and, as notedabove, the improved alloy of the present invention is more controllable as to grain size by variation of the heat treatment than prior alloys of the general type in question. 7 1

In connection with the cobalt and its effect to retain high electrical conductivity, it may be .noted that'the reason for this may be that cobalt has very low solubility in copper, in view of which the cobalt is icombined with the beryllium and does not go directly into solution in the copper.

This is in contrast with some other addition elements which have been employed in copperberyllium alloys and as an illustration, reference ismade to nickel-containing beryllium-copper alloys byway of. comparison. 'In Table A just below are given comparative electrical conductivity figures for two different alloys, one of which contains cobalt and the other nickel; The

figuresrepresent, percentage of conductivity in comparison with. pure copper.

' Table A Be 27 Be 29 Temper C .57; Ni .b'i,

Cu balance Cu balance (a) Annealcd'seit 19. a 11. (h) Heat treated from soft conditio 24. 1 22. (c) Cold drawn i8.4 l5. (d)'Hcat treated from cold drawn condition M 24. 6 20.

l 'ro'm the above tableit will be seen that the alloy with the cobalt addition has materially im-, proved electrical conductivity, especially in the heat treated condition. While some fluctuation in conductivity will result from certain changes i in composition, in accordance with the present invention, the composition is preferably maintained at such figures that they electrical conduc tivity in the hardened condition equals at least 22% that of copper.- 1 1 In TableB just below are given comparative figures for beryllium-copper alloyscontainingcobalt and beryllium-copper alloys containing nickel as to tensile strength of drawn wire with increasing amounts of cold reduction.

Table B B0 2% Be 2% Percentage reduction in area 00 .4 N1 .4%

On balance Cu balance K0. per mm. 6 55 From the above table it will be seen that the beryllium-cobalt-copper alloy is noticeably improved as to tensile strength, especially after extensive cold working.

In carrying out the invention I prefer to operate within the ranges indicated in Table 1 just below: 1

should be within from about 1% to about 2%, although for certain special purposes it may be carried up to about 2.5%.

The ranges of ingredients within which I have secured the best results, especially as to electrical conductivity, are as follows:

Table 2 Per cent Be, from 1.25 to2 Co, from .2 to .5 Cu Balance A specific example of an alloy which I have found to be unusually satisfactory from the standpoint of many physical characteristics, including electrical conductivity, is as follows:

Table 3 1 Per cent BB 2 Co .25 Cu Q Balance With regard to the reference in the above tables of composition to the copper content, 1. e., Cu balance, it is to be understood that this definition as used above and in the appended claims is-intended to include small amounts of addition ingredients and characteristic impurities of copper, such for example as silicon, iron and aluminum. Elements of this type may be present either as addition ingredients or merely as impurities, and in amounts even up to a total of about .3% do not materially alter the characteristic properties of the alloy. I have found, however, that to obtain the maximum conductivity, these other ingredients or impurities should be kept as low as possible and preferably below .l%..

The improved alloy of the present invention is also particularly useful for sand castings which, with other alloys of this general type have had a tendency to develop surface cracks during hardcastings may also be hardened to a very high degree,

-What I claim is: 1. An alloy composed of the following ingredients in the proportions'indicated: I

- Per cent Beryllium .5to 2.5 Cobal c.1to1 Copper Balance 2. -An alloy composed of the following ingredients in the proportions indicated:

- r 1 Per cent Beryllium 1 to 2 Cobalt .1 to 1 Copper. 1 Balance 3. An alloy composed of the following ingredie ents in the proportions indicated:

Per cent Beryllium .L.. 1.25 to 2 Cobalt i .2 to .5

Copper Balance 4. An alloy. composed of the following ents in the proportions indicated:

ingredi- Per cent Beryllium 2 Cobalt"; .25

Copper Balance WERNER HESSENBRUCH. 

